The present invention pertains to a multi-function exercise apparatus which is comprised of a support platform, front and rear frames, footboards, a sliding seat assembly, spring devices and a seat back. Particularly, the sliding seat assembly is mounted on the platform and has the spring devices installed at both sides thereof. Each spring device consists of a spring, a first stem upwardly attached to the seat back and a second stem downwardly secured to the sliding seat assembly, thereby generating a resistant force while propping against the seat back in order to apply the sit-ups performance and synchronize the abdominal exercise with the upper and lower torsos.